In this FIRST award proposal, the investigator proposes to use a rat model of postoperative pain that he has developed. He will test the hypothesis that incisional tissue injury results in a different form of spinal sensitization than that observed in other pain models. In parallel behavioral studies of mechanical hyper-algesia and single unit neurophysiology of spinal dorsal horn neurons, he will examine dorsal horn neuron threshold, receptive field size and background activity before and after incision; the effect of excitatory amino acid antagonists on the hyperalgesia; and the effect of the same antagonists on the sensitized spinal neurons.